Release of nitrogen and phosphorus from sediments observed during a high-frequency field study in brackish Lake Shinji

The release of nitrogen and phosphorus from sediments at high water temperatures was studied by taking weekly measurements at Lake Shinji, a brackish lake in Japan. A severe phosphorus release was observed at high temperatures from August to September. On the other hand, a nitrogen release was observed in July, but not from August to September when the water temperature was higher. Lower nitrite-nitrogen and nitrate-nitrogen concentrations in the water during high water temperature period suggest that the effect of denitrification was minute. The results showed that nitrogen release from sediments in the lake occurs earlier in the year than the phosphorus release.